Background:
We report a prospective, open-label, randomized study to evaluate the safety and efcacy of converting patients with stable renal function from Tacrolimus (Tac)-based regimen to a Sirolimus (SRL)-based regimen after kidney transplantation.

Methods:
Fifty eight low risk renal allograft recipients who were eligible to the study, 6 months posttransplant and receiving Tac, were randomly assigned to continue Tac (n=29) or convert to SRL (n=29). We evaluated the 3-year outcomes including patient and graft survival, graft function and safety profle.

Results:
3-year patient and graft survival in SRL and Tac groups was 93.1% vs. 100% (P=0.04), and 89.7% vs. 100% (P=0.04), respectively. However, the SRL group had signifcantly better renal function, from the second year post-transplant until the last follow-up. Four (13.8%) patients in the SRL group and 3 (10.3%) in the Tac group (P=0.5) developed biopsy proven acute rejection. Mean urinary protein excretion increased signifcantly after SRL conversion. Diastolic blood pressure was signifcantly lower in patients who eliminated tacrolimus (80.4 vs. 75.6 mmHg) (P = 0.03). Mean hemoglobin concentrations decreased after SRL conversion and remained signifcantly lower from 12 months to 36 months (P=0.01). The mean serum cholesterol and triglyceride levels increased signifcantly in the SRL group, (P < 0.05).

Conclusions:
our experience demonstrates that conversion to sirolimus from calcineurin inhibitors (CNI)-based therapy may result in better renal function and blood pressure control in renal transplant recipients without an increased risk of acute rejection. However, these benefts have not resulted in a growing advantage in graft or patient survival.